since you make delivery before Christmas a firm condition,we deeply regret that we cannot supply you as we have done on so many occasions in the past.特别是最后半句as we have done on so many occasions in the past.该如何翻译，谢谢．
热心网友
since you make delivery before Christmas a firm condition,we deeply regret that we cannot supply you as we have done on so many occasions in the past. 既然你使在圣诞节前交货成为定局，那么我们深感抱歉，我们不能像我们以往很多场合下那样给你供货。to have done 表示的是肯定动作,不是 not supply.
热心网友
因为您坚持要求我们在圣诞节前发货，很抱歉，以我们的惯例，我们无法给您供货。最后半句：可以翻译成，就像过去我们对这种情况的处理一样。
热心网友
既然你使在圣诞节前交货成为定局，那么我们深感抱歉，我们不能给你供货，正如我们以往在很多这类场合下的做法一样。